2013's first eclipse is here!! (PARTIAL LUNAR ECLIPSE)

What is a Lunar eclipse?

A lunar eclipse occurs when the moon passes directly behind the earth into its umbra (shadow). This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes. Unlike a solar eclipses, which can only be viewed from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours, where as a total solar eclipse lasts for only a few minutes at any given place, due to the smaller size of the moon's shadow. Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are no brighter (indeed dimmer) than the full moon itself.

 

Partial lunar eclipse

A partial lunar eclipse occurs when only a portion of the Moon enters the umbra. When the Moon travels completely into the Earth’s umbra, one observes a total lunar eclipse. The Moon’s speed through the shadow is about one kilometer per second (2,300 mph), and totality may last up to nearly 107 minutes. Nevertheless, the total time between the Moon’s first and last contact with the shadow is much longer, and could last up to 4 hours. The relative distance of the Moon from the Earth at the time of an eclipse can affect the eclipse’s duration. In particular, when the Moon is near its apogee, the farthest point from the Earth in its orbit, its orbital speed is the slowest. The diameter of the umbra does not decrease appreciably within the changes in the orbital distance of the moon. Thus, a totally eclipsed Moon occurring near apogee will lengthen the duration of totality.

 

What is an UMBRA & PENUMBRA?

Diagram to explain UMBRA & PENUMBRA

    The umbra (shadow) is the innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body. An observer in the umbra experiences a total eclipse.

    The penumbra (almost nearly a shadow) is the region in which only a portion of the light source is obscured by the occluding body. An observer in the penumbra experiences a partial eclipse. An alternative definition is that the penumbra is the region where some or all of the light source is obscured (i.e., the umbra is a subset of the penumbra).

 

 This eclipse (25-26/4/2013)

  The first lunar eclipse of 2013 occurs at the Moon's ascending node in southern Virgo about 12° east of Spica (mv = +1.05). It is visible primarily from the Eastern Hemisphere. The Moon's contact times with Earth's shadows are listed below.

 Penumbral Eclipse Begins: 18:03:38 UT 

 Partial Eclipse Begins: 19:54:08 UT 

 Greatest Eclipse: 20:07:30 UT 

 Partial Eclipse Ends: 20:21:02 UT 

 Penumbral Eclipse Ends: 22:11:26 UT

At the instant of greatest eclipse the umbral eclipse magnitude will reach 0.0147. This event is barely partial with just 0.5 arc-minutes of the Moon's northern limb dipping into umbral shadow. Consequently, the partial phase lasts less than 27 minutes.

Region of visibilitv of eclipse

To catch the entire event, one must be located in eastern Europe or Africa, central Asia or western Australia. At the instant of greatest eclipse the Moon will be at the zenith for an observer just east of Madagascar. Eastern parts of South America will experience moonrise with the eclipse already in progress, but none of the eclipse is visible from North America.

Hope you have a clear sky!!

Enjoy!!